The MCF having a plurality of cores extending along a fiber axis in a common cladding is expected as an optical transmission line capable of transmitting a large capacity of information. On the MCF, various studies have been conducted for the purpose of transmitting a larger capacity of information (e.g., cf. Non Patent Literatures 1 to 7).
Non Patent Literatures 1 and 2 disclose the theories and simulation results about crosstalk between neighboring cores. Furthermore, Non Patent Literatures 3 to 7 disclose the theories and prototyping results about trench-assisted optical fibers.